Abstract

Network-based similarity measures have found wide applications in recommendation algorithms and made significant contributions for uncovering users’ potential interests. However, existing measures are generally biased in terms of popularity, that the popular objects tend to have more common neighbours with others and thus are considered more similar to others. Such popularity bias of similarity quantification will result in the biased recommendations, with either poor accuracy or poor diversity. Based on the bipartite network modelling of the user-object interactions, this paper firstly calculates the expected number of common neighbours of two objects with given popularities in random networks. A Balanced Common Neighbour similarity index is accordingly developed by removing the random-driven common neighbours, estimated as the expected number, from the total number. Recommendation experiments in three data sets show that balancing the popularity bias in a certain degree can significantly improve the recommendations’ accuracy and diversity simultaneously.

Highlights

  • The overwhelming online information, though provides users massive and diverse choices, is making it more and more difficult to find what they really want

  • In this paper we develop a Balanced Common Neighbour (BCN) index for measuring the object similarity in bipartite networks based on the evaluation of the expected common neighbourhood for two objects with specific popularities

  • Countless valuable niche information is hidden in the dominance of popular information

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Summary

Introduction

The overwhelming online information, though provides users massive and diverse choices, is making it more and more difficult to find what they really want. Allocation (RA) index [18] take the user degree as weight to the CN index and read sAαβA = i∈Γα∩Γβ 1/ log(ki) and sRαβA = i∈Γα∩Γβ 1/ki respectively. Though have been widely applied in both analytics of complex networks and the recommender systems, most of the existing similarity indices have systematic popularity bias [12,20,21]. In this paper we develop a Balanced Common Neighbour (BCN) index for measuring the object similarity in bipartite networks based on the evaluation of the expected common neighbourhood for two objects with specific popularities. Applying the proposed method in personalised recommendation, we show that to balance the popularity bias of similarities in a certain degree can largely improve the performances of the recommendations

Balanced object similarity index
Recommendation algorithm and evaluation metrics
Accuracy
Diversity
Results
Discussion

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